RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2024-12-18 17:39:04 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Extend (truncate (load)) folding

Browse Source 
DAGCombiner could fold (truncate (load)) -> smaller load if the original
load was the width of the truncation result or wider.  This patch extends
it to handle cases where the original load was narrower (and so the
extension type stays the same).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197030 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Sandiford 2013-12-11 11:37:27 +00:00
parent 255ee7df29
commit 3c14ba5962
2 changed files with 28 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -5632,6 +5632,20 @@ SDValue DAGCombiner::visitTRUNCATE(SDNode *N) {
SDValue Reduced = ReduceLoadWidth(N);
if (Reduced.getNode())
return Reduced;
// Handle the case where the load remains an extending load even
// after truncation.
if (N0.hasOneUse() && ISD::isUNINDEXEDLoad(N0.getNode())) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
if (!LN0->isVolatile() &&
LN0->getMemoryVT().getStoreSizeInBits() < VT.getSizeInBits()) {
SDValue NewLoad = DAG.getExtLoad(LN0->getExtensionType(), SDLoc(LN0),
VT, LN0->getChain(), LN0->getBasePtr(),
LN0->getMemoryVT(),
LN0->getMemOperand());
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), NewLoad.getValue(1));
return NewLoad;
}
}
}
// fold (trunc (concat ... x ...)) -> (concat ..., (trunc x), ...)),
// where ... are all 'undef'.

14
test/CodeGen/SystemZ/insert-06.ll
View File

@ -178,3 +178,17 @@ define i64 @f14(i64 %a, i64 %b) {
%ext = sext i1 %res to i64
ret i64 %ext
}
; Check another representation of f8.
define i64 @f15(i64 %a, i8 *%src) {
; CHECK-LABEL: f15:
; CHECK-NOT: {{%r[23]}}
; CHECK: lb %r2, 0(%r3)
; CHECK: br %r14
%byte = load i8 *%src
%b = sext i8 %byte to i64
%low = and i64 %b, 4294967295
%high = and i64 %a, -4294967296
%res = or i64 %high, %low
ret i64 %res
}